Tracking the revision separately for part and drawing
Tracking the revision separately for part and drawing
(OP)
Been thinking about having a two part revision number:
1a, 1b, 2a, 3a, 3b, 3c...etc.
The idea is that minor changes (missing a dimension, adding a comment) can be tracked separately from any part design changes.
If a drawing is sent out and I have forgotten a dimension or the client would like an additional comment. I think it would be valuable to issue a new drawing with a minor rev change rather than a full blown new level - kinda like the Solidworks service packs (sp1.0 , sp1.1, sp2.0..etc)
People who see the different revision don't have to be too alarmed knowing that it is just a minor drawing revision and not a design change.
Any thoughts?
1a, 1b, 2a, 3a, 3b, 3c...etc.
The idea is that minor changes (missing a dimension, adding a comment) can be tracked separately from any part design changes.
If a drawing is sent out and I have forgotten a dimension or the client would like an additional comment. I think it would be valuable to issue a new drawing with a minor rev change rather than a full blown new level - kinda like the Solidworks service packs (sp1.0 , sp1.1, sp2.0..etc)
People who see the different revision don't have to be too alarmed knowing that it is just a minor drawing revision and not a design change.
Any thoughts?
Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL
www.kinderdesign.ca






RE: Tracking the revision separately for part and drawing
I.e., revisions that you may consider insignificant may have major impact on suppliers or customers, so you can't always know which are minor and which are not.
Mike Halloran
Pembroke Pines, FL, USA
RE: Tracking the revision separately for part and drawing
Chris
SolidWorks 10 SP4.0
ctopher's home
SolidWorks Legion
RE: Tracking the revision separately for part and drawing
Once a single print or file leaves your premises/control, any kind of informal revision system presents a risk.
Mike Halloran
Pembroke Pines, FL, USA
RE: Tracking the revision separately for part and drawing
Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion
&
RE: Tracking the revision separately for part and drawing
Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion
&
RE: Tracking the revision separately for part and drawing
Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL
www.kinderdesign.ca
RE: Tracking the revision separately for part and drawing
If you want to distinguish between major and minor changes, write it up in the revision block.
"CORRECTED SPELLING MISTAKE ON SECTION A-A. NO CHANGE TO INFORMATION ON DRAWING."
"LENGTH CHANGED FROM 77.4. NO PARTS FABRICATED TO ORIGINAL RELEASE."
"ADDED TWO HOLES. ALL EXISTING PIECES MODIFIED TO NEW REVISION."
As noted above, you cannot have two parts fabricated to the same drawing, with same part number, that are not functionally identical.
RE: Tracking the revision separately for part and drawing
The thing you need to keep in mind is whether your PDM/MRP/ERP system can handle 2 different revisions for a given part. Many will blow-up.
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: Tracking the revision separately for part and drawing
That would be confusing.
Chris
SolidWorks 10 SP4.0
ctopher's home
SolidWorks Legion
RE: Tracking the revision separately for part and drawing
Revision block is definitely one way of doing it and certainly is "textbook" (change triangle + revision table)
Most of the jobs and clients I work for - I feel it would be overkill (i.e I'm looking for a easier/lazier/efficient way of doing things.
My feeling is that if the change is really just a clerical change and not a functional change - a small indicator is all that is needed.
Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL
www.kinderdesign.ca
RE: Tracking the revision separately for part and drawing
Let me through some of my experience in the ring.
The important thing to realize when talking about having to track revisions, is how does the rest of the company treat the revision?
I can tell you most customers I have dealt with do not track revisions outside of the company. That is because it is very difficult from an MRP perspective to track a change that doesn't affect form/fit/function yet must be revised for various reasons. In addition almost all companies who make changes to a part that are significant enough that the new part is no longer interchangeable with the old part demand that you take out a NEW part #. This again is not due to CAD it is due to the MRP package and how the rest of the organization tracks and controls inventory. I had one customer who actually labeled ALL parts with partnumber AND rev. But after a while they realized this was expensive and didn't yield that much of a benefit since they still couldn't see how many of each REV was in inventory. Long story short, I don't know of any company who USES minor revisions THROUGH-OUT the organization. Lots of companies I work with only use that type of control during the developement process and internal to engineering. Usually these companies have that process integrated with in PDM system so to the user it is fairly a brainless automatic activity going on with out there awareness.
My recommendation, Go with Numbers . . . no minor revisions. especially if you don't have an integrated PDM.
And finally ask yourself what would be the difference in the process between a minor revision and a major revision, if the answer is "I put a small letter after the number" then it probaly is a headache in the making.
StrykerTECH Engineering Staff
Milwaukee, WI
http://www.stryker-tech.com/
RE: Tracking the revision separately for part and drawing
What I would like to avoid is saying "Ignore the previous file and let this one overwrite it.."
Again, for a missing dimension or a dxf/dwg that was exported at the wrong scale - a full blown revision is overkill and I would to save the client from looking at what is different.
Of course, the revision table would pinpoint what the change was but that just makes the designers/drafter job more difficult with more clerical work. Plus those revision tables take up alot space. If these were mass produced carefully controlled documents - then for sure, do it textbook. But for the smaller jobs - one offs, looser clients - a system to communicate minor, clerical changes, the two part system is sounding good.
Also, one more thing I've been doing lately is appending the rev to the pdf and autocad file. This way at a glance I know what is going on and if I have the two part system, the file names will be unique, no overwriting neccessary.
Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL
www.kinderdesign.ca
RE: Tracking the revision separately for part and drawing
If you are issuing drawings to customers, you need to identify which ones are correct. On preliminary design layouts, I have a note stating explicitly that the drawings are preliminary, and showing the latest date.
An any final, official communications, you need a revision letter or number. The whole point of bureaurocracy is that the left hand does not know what the right hand is doing. If I see one copy at Rev_B and one at Rev_C, I know one print is superseded, and I know which one. Notes on the drawing can be hard to spot. Cover letters and emails might not get passed on to me. I can send you an email asking what the current revision of the drawing is, thus, quickly validating my information.
RE: Tracking the revision separately for part and drawing
Make your drawings/files match the ones you send to customers or vendors, minor or rev or not, then there will be no question.
Chris
SolidWorks 10 SP4.0
ctopher's home
SolidWorks Legion
RE: Tracking the revision separately for part and drawing
StrykerTECH Engineering Staff
Milwaukee, WI
http://www.stryker-tech.com/
RE: Tracking the revision separately for part and drawing
Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL
www.kinderdesign.ca
RE: Tracking the revision separately for part and drawing
StrykerTECH Engineering Staff
Milwaukee, WI
http://www.stryker-tech.com/
RE: Tracking the revision separately for part and drawing
Strytech does raise a good point about scalability. Would this work in a bigger company? Traditionally, all drawings get bumped to a new rev, no matter what the change was. This system definitely does work but then we must ask ourselves, does it create extra work, is there a better way to do it?
The rev block does take time to do, adding the descriptions is a pain and the rev block takes up valuable real estate, Of course, certain products do require this type of control but I feel that many do not.
Tim Chung
Mechanical Designer, CSWP+WLDMNTS+SHTMTL
www.kinderdesign.ca
RE: Tracking the revision separately for part and drawing
Peter Stockhausen
Senior Design Analyst (Checker)
Infotech Aerospace Services
www.infotechpr.net
RE: Tracking the revision separately for part and drawing
I still feel that no matter what you decide, you still have to outline what will be different between the two processes.
I know from my own experience, a minor revision process can work when implemented in a small company where there aren't many functional areas and people inherently know more about all aspects of the organization. That being said, when you lay out the differences in the process I bet you will find all sorts of holes on how the process could break down. As you fill up the holes you will eventually find yourself right back at the original REV process.
To the comment about what to put on the drawing, I prefer to put as littel description about the REV as possible. I would rather handle that via another document that can be changed and added to by other departments. This makes the drawing more automatic. Most companies I have set processes up for, have likened to the fact that the drawing just cycles the REV based on a PDM system. This keeps manual interaction down and eliminates the possibility of mistakes. Plus no one likes putting REV on a drawing to change the previous REV's description block error of some sort. That is a vicous circle.
StrykerTECH Engineering Staff
Milwaukee, WI
http://www.stryker-tech.com/
RE: Tracking the revision separately for part and drawing
When you add information to a document, you have to ask yourself what the end user needs and is authorized to know. An external vendor with tooling or CAM programming needs to know what you have changed on a fabrication drawing.
I regard ECRs as proprietary. I would not let these outside the company. Also, I have seen a lot of drawings marked AS PER ECO such and such. I have pulled out the ECO and found that it has nothing whatsoever to do with the drawing. Maybe your office is better disciplined than mine.
RE: Tracking the revision separately for part and drawing
Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion
&
RE: Tracking the revision separately for part and drawing
you make a good point, but ultimately any system is predicated on the people executing it. So if people are not disciplined the system will fail in some aspect as some point. I have seen changes that you couldn't put enough information on the drawing to convey what has changed, in that case an ECO is almost unavoidable. Furthermore, depending on the dynamics of the business, a drawing can last a long time and it becomes impractical tracking its history on the drawing.
StrykerTECH Engineering Staff
Milwaukee, WI
http://www.stryker-tech.com/
RE: Tracking the revision separately for part and drawing
We subcontract all of our fabrication. I assume that my fabrication drawings are public information. There is no telling where they will wind up, even if the fabricator signs an NDA. All it takes is for a worker to take a drawing home to show an nephew who is interested in becoming a CAD operator.
The ECO and/or the revision block ought to state something like "DIM 1.650 CHANGED TO 1.660". This is harmless, even in the hands of a competitor, or Mahmoud Ahmadinejad, or Michael Moore, or Brittney Spears.
A well written ECR could state that an undersized plug is a safety hazard, and/or provide a detailed explanation of how your stuff works (or not). Your outside vendor only needs to know the change on the part.
Even if you do your fabrication in-house, are you sure the drawing will not be sub-contracted, later?
RE: Tracking the revision separately for part and drawing
Ask any software maker and they will tell you its absolutley necessary to have minor revisions and almost all have adopted it - from internet explorer I am viewing in his page 8.0.7600.16385
We have a number of geographical sites so pre-production, whilst designs are being reviewed via pdf, we use numeric revisions on drawings to track production/design comments design which alter the way a part is made. Here the rev table has a ref column for any external references such as ECO XYZ or other
Once its agreed on the drawing is Released at a nice clean Rev A (alphabetical) and the older development pdf say Rev 13 is filed away in the components design history. We generally save up minor changes to drawings and correct missing dims at the end of a production cycle if not important. If however we are asked by a suppplier we will up rev for anything no matter how minor.
This was an attempt to keep track of the numerous design changes in the cycle and promoted the designers not to be afraid of releasing as many drawings for review as necessary & the option of using a single document to track design process.
I believe having an ISSUE # box on tile block also another method. But as somone alluded to this can get confusing as you will have release 2.A for example (Issue 2, rev A).
It suits us for what we do but as this discussion comes up so very often the world is a big place & everyone has a system that suites them - KISS.
RE: Tracking the revision separately for part and drawing
Colin Fitzpatrick (aka Macduff)
Mechanical Designer
Solidworks 2010 SP 3.1
Dell 490 XP Pro SP 2
Xeon CPU 3.00 GHz 3.00 GB of RAM
nVida Quadro FX 3450 512 MB
3D Connexion-SpaceExplorer
RE: Tracking the revision separately for part and drawing
Read up on type numbers of American and German aircraft during WWII. They did major and minor revisions.
I think that major and minor revisions are a valid concept at the final product level. At the level of my connector panel, or your C++ file containing one method, all we care about is whether or not something changed. At this level, KISS applies.